This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In the absence of an effective vaccine, other methods for preventing the sexual transmission of human immunodeficiency virus type 1 (HIV-1) must be pursued. Recently, increased attention has been placed within the wider vaccine research field on the notion that non-neutralizing Abs may protect against HIV-1 transmission, and should therefore be induced by a vaccine. To investigate this hypothesis in a more definitive manner we are performing a two-stage experiment involving both the vaginal and the systemic delivery of test MAbs, and the use of 24 rhesus macaques, in total. These macaque studies are currently being carried out at the Tulane National Primate Research Center, using na[unreadable]ve Rhesus macaques of Chinese origin. Macaques treated with non-neutralizing and neutralizing antibodies will be assessed and compared for their ability to protect against vaginal SHIV transmission.